Aww ffs.
Nursery rhymes were found a really long time ago. Most of the old ones were meant to scare the children to sleep ('Sleep, baby, sleep.. If you don't sleep, a wolf will come and eat you'... and stuff like that), because they wouldn't go to bed earlier.
There are tons of nursery rhymes, that contain 'violent rhymes'. It's plain normal. Either you're trying to make something big out of nothing, or you're just having a laugh..